Novel paper sizing process



United States Patent "ice This invention relates to a process for thesizing of paper and to the improved paper thus prepared. Moreparticularly, this invention relates to novel sizing agents for use inthe sizing of paper and paperboard products.

It is the object of this invention to provide improved sizing agentswhose use results in the preparation of paper which is characterized byits reduced water and ink absorption [as Well as its resistance toaqueous acid and alkaline solutions. A further object of this inventioninvolves the use of sizing agents which may be employed with all typesor" paper pulp over the complete range of pH conditions which arenormally encountered in paper manufacturing. An additionalobjectinvolves the use of sizing agents which are fully compatable withalum and rosin as well as with the various fillers, pigments and otherchemicals which may be added to paper.

As used herein, the terms paper and paperboard include sheet-like massesand molded products made from fibrous cellulosic materials which may bederived from both natural and synthetic sources. Also included aresheetdike masses and molded products prepared from combinations ofcellulosic and non-cellulosic materials derived from synthetics such aspolyamide, polyester and polyacrylic resin fibers as well as frommineral fibers such as asbestos and glass.

Paper and paperboard are often sized with various materials for thepurpose of increasing their resistance to Water as well as to othertypes of aqueous solutions. These materials are referred to as sizes orsizing and they may be introduced during the actual paper makingoperation wherein the process is known as internal or engine sizing. Or,on the other hand, they may be applied to the surface of the finishedweb or sheet in which case the process is known as external or surfacesizing.

Various wateruepellant materials have been utilized as sizing agents.These include rosin, mixtures oirosin with waxes, wax emulsions, ketenedimer emulsions, fluorocarbons, fatty acid complexes of chromium or"aluminum chlorides, long chain thermoplastic copolymers, @as well assome themnosetting condensation type resins. Although all of t esematerials are effective under certain conditions, their use isnonethless subject to one or more limitations.

Thus, for example, in the case of rosin, although the latter isrelatively low in cost and readily available, it has poor resistance toalkaline solutions and cannot be used for the sizing of neutral oralkaline pulps. It is inoperable with the latter since it must beordinarily used in combination with alum, or an acidic aluminum iondonor, which-is present for the purpose of precipitating and setting thesodium rosinate, i.e. the rosin soap, onto the fibers. The use of alumfor this purpose is, however, precluded under neutral or alkalineconditions. This is a definite disadvantage since the paper producedfrom neutral and alkaline pulp has been found to have higher strength,greater stability and superior aging charv aliases Patented Aug. 27,1963 actenistics in comparison with the paper prepared from acidic pulp.Also, the internal use of alkaline pigments such as calcium carbonate isprecluded. This same limitation also applies to the use of most waxemulsions which cannot be used on the alkaline side since they areusually combined with small quantities of alum for the purpose ofbreaking the emulsions. On the other hand,

certain sizing agents-will not tolerate appreciable quantities of alumor high acidic conditions. In some cases, it may be desirable ornecessary to use alum for filler retention purposes, for increasingsheet drainage, or to retain or set condensation resin additives, etc.Certain sizing agents cannot be adequately retained in the sheet duringsheet formation and, consequently, are limited only to external orsurface applications.

In addition to the above described pH limitations, the Water resistanceor water holdout which is attainable with many of the heretoforeemployed sizing agents is cite-n inadequate for many applications whichmay require paper or paperboard displaying an exceptionally high degreeof Water resistance. Moreover, many of these sizing agents have beenfound to be incompatible with the pigments, fillers, or otheringredients which often are added to paper. A further disadvantage ofsome sizing agents is that a considerable degree of heat curing isrequired to develop full effectiveness. Thus, in using these materials,full effectiveness and full sizing value may not be obtained immediatelyafter formation and drying of the paper web.

We have now discovered that the use of certain reagents as sizes torpaper and paperboard has been found to result in the preparation ofproducts which display an unusually high degree of water resistancealong with resistance of acidic and alkaline solutions. Oi primeimportance is the fact that the successful use of these new sizingagents is not restricted to any particular pH range which thus allowsfor their utilization in the treatment of neutral and alkaline pulp asWell its acidic pulp. Our sizing agents may also be used in combinationwith alum as well as with any of the pigments, fillers and otheringredients which may he added to paper. Still another advantage ofthese sizing agents is that they may be used in conjunction with othersizing agents so as to obtain additive sizing effects. A still furtheradvantage of these sizing agents is that they do not detract from thestrength of the paper and when used with certain adjuncts will in tact,increase the strength of the finished sheets. An additional advantage ofour novel sizing agents is that only mild drying or curing conditionsare required to develop full sizing value.

The novel sizing agents-of our invention may be described as substitutedcyclic dicarboxylic acid anhydrides corresponding to the followingstructural formula:

wherein R represents a :dimethylene or trimethylene radical and whereinR a hydrophobic group containing more than 5 carbon atoms which may beselected from the class consisting of alkyl, alkenyl, aralkvl oraralkenyl groups. Substituted cyclic dicarboxylic acid anhydrides 3falling within the above described formula are the substituted succinicand glutaric acid 'anhydrides.

Specific examples of the above described sizing agents includeiso-octadecenyl succinic acid anhydride, n-hexadecenyl s uccinic acidanhydride, dodecenyl succinic acid anhydride, dodecyl succinic acidanhydride, decenyl succinic acid anhydride, octenyl succinic acidanhydride, noneny-l succinic acid anhydride, triisobutenyl succinic acidanhydride, capryloxy succinic acid anhydride, heptyl glutaric acidanhydride, and benzyloxy succinic acid anhydride. From among thereagents of this type, we have found that optimum results are obtainedwith acid anhydrides in which R contains more than twelve carbon atoms.It should also be noted that it is possible to employ mixtures of any ofthese reagents in the process of our invention.

The actual use of our novel sizing agents in the manufacture of paper issubject to a number of variations in technique any of which may befurther modified in light of the specific requirements of thepractitioner. It is important to emphasize, however, that with all ofthese procedures, it is most essential to achieve a uniform dispersal ofthe sizing agent throughout the fiber slurry, thereby necessitating thatits addition to the pulp be accompanied with prolonged and vigorousagitation. Uniform dispersal may also be obtained by adding the sizingagent in a fully dispersed form such as an emulsion; or, by thecoaddition of chemical dispersing agents to the fiber slurry.

Another important factor in the effective utilization of the sizingagents of our invention involves their use in conjunction with amaterial which is either cationic in nature or is, on the other hand,capable of ionizing or dissociating in such a manner as to produce oneor more cations or other positively charged moieties. These cationicagents, as they will be hereinafter referred to, have been found usefulas a means for aiding in the retention of our sizing agents as Well asfor bringing the latter into close proximity to the pulp fibers. Amongthe materials which may be employed as cationic agents in the process ofour invention, one may list alum, aluminum chloride, long chain fattyamines, sodium aluminate, polyacrylamide, chromic sulfate, animal glue,cationic thermosetting resins and polyamide polymers. Of particularinterest for use as cationic agents are various cationic starchderivatives including primary, secondary, tertiary or quaternary aminestarch derivatives and other cationic nitrogen substituted starchderivatives, as well as cationic sulf-onium and phosphonium starchderivatives. Such derivatives may be prepared from all types of starchesincluding corn, tapioca, potato, waxy maize, wheat and rice. Moreover,they may be in their original granule form or they may be converted topregelatinized, cold water soluble products.

Any of the above noted cationic agents may be added to the stock, i.e.the pulp slurry, either prior to, along with or after the addition ofthe sizing agent. However, in order to achieve maximum distribution, itis preferable that the cationic agent be added either subsequent to orin direct combination with the sizing agent. The actual addition to thestock of either the cationic agent or the sizing agent may take place atany point in the paper making process prior to the ultimate conversionof the wet pulp into a dry web or sheet. Thus, for example, our sizingagents may be added to the pulp while the latter is in the headbox,beater, hydropulper or stock chest.

In order to obtain good sizing, it is desirable that our sizing agentsbe uniformly dispersed throughout the fiber slurry in as small aparticle size as is possible to obtain.

'One method for accomplishing this is to emulsify the sizing agent priorto its addition to the stock utilizing either mechanical means, such ashigh speed agitators, mechanical homogenizers, or ultrasonichomogenizers, or by the addition of a suitable emulsifying agent. Wherepossible, it is highly desirable to employ the cationic agent as theemulsifier and this procedure is particularly successful where cationicstarch derivatives are utilized. Among the applicable non-cationicemulsifiers which may be used as emulsifying agents for our sizingagents, one may list such hydrocolloids as ordinary starches,noncationic starch derivatives, dextrines, carboxymethyl cellulose, gumarabic, gelatin and polyvinyl alcohol as well as various surfactants.When such non-cationic emulsifiers are used, it is often desirable toseparately add a cationic agent to the pulp slurry after the addition tothe latter of the emulsified sizing agent. In preparing these emulsionswith the use of an emulsifier, the latter is first dispersed in waterand the sizing agent is then introduced along with vigorous agitation.If the sizing agent normally exists as a Waxy solid, it must first bemelted prior to its emulsification.

Further improvements in the water resistance of the paper prepared withour novel sizing agents may be obtained by curing the resulting webs,sheets or molded products. This curing process involves heating thepaper at temperatures in the range of from to C. for periods of from 1to 60 minutes. Such post curing is particularly recommended where use ismade of those sizing agents of our invention having hydrophobic groups(i.e. R in the above described formula) containing 12 or less carbonatoms. However, it should again be noted that post curing is notessential to the successful operation of our sizing process.

The sizing agents of our invention, may, of course, be successfullyutilized for the sizing of paper prepared from all types of bothcellulosic and combinations of cellulosic with non-cellulosic fibers.The cellulosic fibers which may be used include bleached and unbleachedsulfate (kraft), bleached and unbleached sulfite, bleached andunbleached soda, neutral sulfite, semi-chemical, chemigroundwood, groundwood, and any combination of these fibers. These designations refer towood pulp fibers which have been prepared by means of a variety ofprocesses which are used in the pulp and paper industry. In addition,synthetic fibers of the viscose rayon or regenerated cellulose type canalso be used.

All types of pigments and fillers may be added to the paper which is tobe sized with our novel sizing agents. Such materials include clay,talc, titanium dioxide, calcium carbonate, calcium sulfate, anddiatomaccous earths. Other additives, including alum, as well as othersizing agents can also be used with our sizing agents.

With'respect to proportions, our sizing agents may be employed inamounts ranging from about 0.05 to about 5.0% of the dry weight of thepulp in the finished sheet or web. Within this range the precise amountwhich is to be used will, of course, depend for the most part upon thetype of pulp which is being utilized, the specific operating conditions,as well as the particular end use for which the paper is destined. Thus,for example, paper which will require good water resistance or inkholdout will necessitate the use of a higher concentration of sizingagent than paper which will be used in applications where excessivesizing is not needed. These same factors also apply in relation to theamount of cationic agent which may be used in conjunction with oursizing agents. Thus, the practitioner will be able to use thesematerials in any concentration which is found to be applicable to hisspec1fic operating conditions. However, under ordinary circumstances arange of from 0.5 to 2.0 parts by weight of cationic agent per 1.0 partof sizing agent is usually adequate. Thus the cationic agent is in aquantity at least 0.025% of the dry weight of the pulp in the paper. Inthose cases where use is made of those sizing agents of our inventionhaving hydrophobic groups containing l2 or less carbon atoms, it isadvisable to employ these cationic agents in concentrations near theupper limit of this range.

In any event, the use of our reagents has been found to provide a degreeof water resistance which is comparable, and in many cases superior, tothe results obtained with other heretofore employed sizing agents.Moreover, our sizing agents impart a resistance to acid and alkali whichis often unattainable with other sizing agents.

The following examples will further illustrate the embodiment of ourinvention. In these examples all parts given are by weight unlessotherwise noted.

Example I This example illustrates the use of our sizing agents in theform of aqueous emulsions wherein the emulsifier used is a tertiaryamine cationic starch derivative. The use of our sizing agents incombination with alum is also illustrated. The water resistance of theresulting paper is compared with that of paper which had been sized withmixtures of fortified rosin and alum.

An aqueous emulsion of iso-octadecenyl succinic acid anhydride which forpurposes of brevity will hereinafter be referred to as IODSA, wasprepared by first cooking 7.5 parts of the beta-diethyl amino ethylchloride hydrochloride ether of corn starch, whose preparation isdescribed in Example I of US. Patent 2,813,093, in 85 parts of waterwhich was heated in a boiling water bath. After being cooked for 20minutes, the dispersion of the cationic starch derivative was cooled toroom temperature and transferred to a high speed agitator whereupon 7.5parts of IODSA were slowly added to the agitated dispersion. Agitationwas continued tor 5 minutes and the resulting emulsion was then dilutedby the addition of another 900 parts of water. A final fold dilution wasthen effected and this was added to an aqueous slurry of bleachedsulfate pulp having a consistency of 1.5% and pH of about 8.5. Sheetswere formed and dried in accordance with TAPPI standards and the lattercontained 1%, as based on the Weight of the dry pulp, of

both the cationic agent and the IODS A. The basis weight of these sheetswas 55 lbs./ ream (24 x 36"500 sheets). By means of the same procedurecomparable sheets were made which contained varying amounts of IODSA aswell as several which contained the IODSA in combination with varyingamounts of alum. In all cases where alum was used, the pH of the aqueouspulp slurry was 5.0.

The water resistance of these sheets was compared with that of sheetsprepared from comparable pulp which had been sized with a mixture ofrosin and alum. In comparing the water resistance of these sheets, weused the uranine dye test and the ink dip test. The former test involvesplacing a small amount of uranine dye powder on the upper surface of aswatch of paper which is. then set afloat in distilled water. As thewater is absorbed into the paper, the dye is moistened and thus becomessensitive to ultraviolet light. The time, in seconds, required for thisUV sensitivity to occur is thus in direct relation to the waterresistance of the paper since a more water resistant paper will, ofcourse, retard the moistening of the dye which has been placed upon itsupper surface.

The ink dip test is a qualitative comparison wherein a swatch of thepaper being tested is dipped into a 1:1 mixture of water and blue ink.The swatch is then removed, washed with water and the remaining colorevaluated with a colorimeter. Thus, a swatch with a greater degree ofwater resistance will have a lighter color than a swatch with poor waterresistance. For this test an arbitrary color scale of 1-10 was used,with #1 indicating .the least color or the best water resistance, andthe #10 indicating the most color or the poorest water resistance. Thistest also provides a qualitative visual indication of the distributionof the sizing agent in the paper.

The follown gtable presents data on the various sheets which werecompared and gives the results obtained with both the uranine dye andthe aquapel dip tests.

Percent, Uranine dye Ink dip Sheet N o. Additives by wt, test (time test(color of dry in sec.) value) 1 llone 1.1 i- Immediate 1O ationic cornstare 2 {IODSA 1 i 105 3 Cationic corn starch. 1 3 IODSA 1 118 2 fil i aionic corn s are 1O 4 {IODSA 3 i 130 1 Cationic corn stareh 3 5. IODSA 3132 1 Z a route corn s are 6 ODSA i 138 1 2 7s 5 Example 11 This exampleillustrates the use of varying concentrations of IODSA and thus pointsout the improved Water resistance which is obtained when this reagent isused at various concentrations.

A series of aqueous emulsions of IODSA were prepared by means of theprocedure described in Example I wherein the same tertiary aminecationic starch described therein was again used as the emulsifier.These emulsions contained varying amounts of both the IODSA and thecationic starch and, with agitation, they were added, at the headbox, toseparate batches of bleached sulfate pulp having a fireeness of 500 anda consistency of 0.5 In all cases, the pH of the pulp slurry was-8.0except where rosin was used in which case the resultant pH of the slurryafter addition of the alum was 4.5-5.0. The basis weight of theresulting paper was 60 lbs/ream. Below are described the compositions ofthe various sheets which were prepared as well as the results obtainedwhen the Water resistance of these sheets was tested by means of theuranine dye test.

Percent, Uranine dye Sheet No. Additive by Wt., test (time of dry insec.)

1 None Immediate 2 {Cationic corn starch" 0.25 92 IODsA .25

1, 8 116 3 134 :8 149 1. m i 94 7 {Alum 4: 0 i 124 Example III Thisexample illustrates the use of octenyl succinic acid anhydr-id-e. Italso illustrates the importance of using the latter in combination withalum as well as the desirability for the post curing of the sheets sizedwith this short chain length derivative so as to obtain sizing resultswhich are comparable to those obtained with longer chain derivatives.

An aqueous emulsion of octenyl succinic anhydride was prepared by meansof the procedure described in Example I. The same cationic starchderivative was used as the emulsifier; however, in this case thederivative was pregelatinized, i.e. put into cold water soluble form, by

passing an aqueous slurry of the derivative over heated metal idrums.By'employing the cationic starch in this pregelatinized form it was, ofcourse, unnecessary to cook it up in order to disperse it. Withagitation, the resulting emulsion of octenyl succinic acid anhydride wasthen added to a bleached sulfate stock having a f-reeness of 500 and aconsistency of 1.5%. The slurry was then 7 diluted to a 0.5% consistencyand a quantity of alum was introduced. After the addition of the alum,the pH of the slurry was 5.5. The basis weight of the resulting sheetswas 60 lbs/ream. These sheets contained 1.0% of both octeny-l succinicacid anhydride and the cationic starch, and 2.0% of alum as based uponthe dry weight of the pulp. They were then cured for 1 hour at 105 C.For comparative purposes, additional sheets were prepared wherein anaqueous emulsion of IODSA, prepared With the cationic starch derivativedescribed in Example I was used as the sizing agent; and, in anothercase, where a mixture of fortified rosin and alum were used. Howeverwith both of these latter procedures there was no post curing of theresulting sheets. The pH of the particular pulp slurry containing theIODSA was 8.0. Below are described the compositions of the varioussheets which were prepared as well as the results obtained when thewater resistance of these sheets was tested by means of the uranine dyetest.

Example I V This example illustrates the use of IODSA in its oily,unemulsified form and demonstrates the improvements obtained when, inone case, a cationic agent is added to the stock after the addition ofthe unemulsified IODSA; and, in another case, when ordinary corn starchis added to the stock before the addition of the IODSA and a cationicagent, the purpose of the corn starch being to aid in the dispersion ofthe sizing agent; and, in still another case, where corn starch is addedto the stock prior to the addition of only the unemulsified IODSA.

With agitation, a quantity of IODSA was added to bleached sulfate pulphaving a freeness of 500 and a 1.5% consistency. This quantity wassufiicient to provide the finished sheets with a concentration of IODSAequivalent to 1.0%, by weight, of the dry pulp. Under comparableconditions sheets were then prepared wherein the following changes weremade: (1) corn starch was added to the pulp prior to the addition of theunemulsified IODSA; (2) the cationic starch described in Example I wasadded to the pulp after the addition of the unemulsified IODSA; and (3)corn starch was added to the pulp prior to the addition of theunemulsified IODSA which was then followed by the addition of thecationic starch described in Example I. The basis weight of all of theabove described sheets was 55 lbs/ream (24 x 36500 sheets). Below aredescribed the compositions of the various sheets which were prepared aswell as the results obtained when the water resistance of these sheetswas tested by means of the uranine dye test.

8 Example V This example illustrates the use of ordinary corn starch asthe emulsifying agent for IODSA.

An aqueous emulsion of IODSA was prepared using the procedure of ExampleI; however, in this case, ordinary corn starch rather than the cationicstarch derivative was used as the emulsifier. With agitation, thisemulsion was added to bleached sulfate pulp having a freeness of 500 anda 1.5% consistency. This was followed by the addition of alum to a pH of5.5. The finished sheets contained 1.0% of IODSA and 1.0% of corn starchas based upon the dry weight of the pulp and had a basis weight of 60lbs/ream. Below are described the compositions of the various sheetswhich were prepared as well as the results obtained when the waterresistance of these sheets was tested by means of the uranine dye test.A comparison of sheets which had been sized with fortified rosin andalum is also offered.

Example VI This example illustrates the use of IODSA for the sizing ofpaper containing an appreciable quantity of inert pigments.

An aqueous emulsion of IODSA was prepared using the procedure of ExampleI. With agitation, portions of this emulsion were added to a series ofbleached sulfite pulps having a freeness of 440 and a consistency of 1.5and which also contained, respectively, 10% of titanium dioxide, 10% ofcalcium carbonate, and 10% of clay as based upon the dry weight of thepulp. The resulting sheets each contained 0.5% of IODSA and 0.5% byweight of the cationic starch derivative as based upon the dry weight ofthe pulp and had a basis weight of 60 lbs./ ream. Below are describedthe compositions of the various sheets which were prepared as well asthe results obtained when the water resistance of these sheets wastested by means of the uranine dye test. A comparison of pigmentcontaining sheets which had been sized with fortified rosin and alum isalso offered.

Example VII This example illustrates the use of IODSA in its oily,unemulsified form which was, however, added to the pulp in combinationwith a cationic starch.

With agitation, separate portions of IODSA and the cationic corn starchderivative described in Example I were added, simultaneously, to amixture of 73% groundwood and 27% bleached sulfite pulps having afreeness of 350 and a consistency of 1.5%. The resulting sheetscontained 1.0% of IODSA and 1.0% of the cationic corn starch as basedupon the dry weight of the pulp. The

' Percent, Uranine dye Sheet No. Additives by wt., test (time of dry insec.)

Cationic corn starch 1. {IODSA 1. i 104 Example VIII This exampleillustrates the use of IODSA in the form of an emulsion prepared with anon-cationic, starch derivative emulsifier. The resulting emulsion wasthen used in combination with a cationic starch.

-An aqueous emulsion of IODSA was prepared by means of the proceduredescribed in Example 1. However, in this case, the emulsifier which wasused was a corn starch acid ester of octenyl succinic acid as preparedby means of the procedure described in Example H of US. Patent2,661,349. With agitation, this emulsion along with a quantity of thecationic corn starch derivative described in Example I of thisdisclosure, were added, at the headbox, to a bleached sulfate pulphaving a freeness of 500 and a consistency of 0.5. The resulting sheets,in this case, contained 1.0% of IODSA, 1.0% of the corn starch acidester emulsifier, and 1.0% of the cationic starch as based upon the dryweight of the pulp. Below is described the composition of the sheetsprepared as well as the results obtained when the water resistance ofthese sheets was tested by means of the uranine dye test. A comparisonof sheets which had been sized with fortified rosin and alum is alsooffered.

Percent, Uranine dye Sheet No. Additives by Wt., test (time ofdry insec.)

Corn starch acid ester 1. 0 1 IODSA 1.0 139 gatiogiiel corn starch ortie rosin. a. {Alum 2. 0 i 115 Example IX This example illustrates the useof IODSA in the form of an emulsion wherein a number of differentcationic corn starch derivatives were each used, respectively, as theemulsifying agent.

Listed below are the various cationic amine corn starch derivatives usedas emulsifiers along with a brief description of the method used fortheir preparation.

(A) Primary amine corn starch-Prepared by reacting 100 parts of cornstarch, 20 parts of ethylene imine and parts of toluene in a pressurevessel for 20 hours at a temperature of 60 C. The product was recoveredby the addition of 200 parts of methanol and 35.7 parts of concentratedhydrochloric acid and was then filtered,

amine corn starch derivative.

(C) Quaternary starch amine.Prepa'red by reaction of corn starch withthe reaction product of triethylamine and epiohlorohydrin as describedin Example I of US. Patent 2,876,217.

10 Each of the above described starch amines was then used as theemulsifier for the preparation of aqueous emulsions of IODSA. Theseemulsions were each, in

turn, added to bleached sulfate pulp having a freeness of Percent,Uranine dye Sheet No. Additives by wt test (time in of dry See.)

{Primary amine corn starch 1. 0 193 ISODSx 1 it econ a amine corn s are.0 {IODtqA W t h l ua ernary amine com S are 0 {ibosx i 128 2: 0 I 98Example X This example illustrates the use of IODSA in the form of anemulsion wherein a number of cationic amine derivatives of variousstarch bases were each, respectively, used as the emulsifying agent. Theimprovements in Water resistance obtained by post curing are alsodemonstrated.

The various emulsifiers used were the tertiary amine, beta-diethyl aminoethyl chloride hydrochloride starch ethers prepared as described inExample I, of US. Patent 2,813,093. However, in place of the corn starchbase, we substituted a variety of starch bases including waxy maize,tapioca, potato, a waxy maize starch which was acid converted to adegree known in the trade as fluidity, land a corn starch which was acidconverted to a degree known in the trade as 75 fluidity.

Each of the above described tertiary starch amines was then usedas theemulsifier for the preparation of aqueous emulsions of IODSA. Theseemulsions were each, in turn, added at the headbox to bleached sulfatepulp having a freeness of 500 and a consistency of 0.5%. The resultingsheets in each case, contained a 1.0% of IODSA and 1.0% respectively, ofthe various tertiary amine starches as based upon the dry weight of thepulp. The water resistance of these sheets was then evaluated by meansof the uranine dye test, as described in Example 1. Additional samplesof these sheets were then cured by being heated for 1 hour at atemperature of C. The water resistance of these cured sheets wassimilarly determined by means of the unanine dye test. The results ofthese tests are presented in the following table.

, Uranine dye test Percent, (time in sec.) Sheet Additives by wt, No. ofdry pulp Immedi- Cured ate Waxy maize tertiary amine 1. 0 1 {IODSA %.0 i102 102 .0 i8 118 L0 112 11s Acid conv. waxy maize tert. 1.0 4 amine. 8393 IODS. 1.0 Acid eonv. corn starch tert. 1.0 5 amine. 95 109 IODSA 1.0

1 1 Example XI This example illustrates the use of several of the sizingagents of our invention including n-hexadecenyl succinic acid anhydride,dodecenyl succinic acid anhydride, dodecyl succinic acid anhydride, anda mixture of iso-alkenyl succinic acid anhydrides wherein the alkenylgroups of the mixed anhydrides contained from 18 to 22 carbon atoms.

An aqueous emulsion of each of the above described sizing agents wasprepared by means of the procedure described in Example I using, as anemulsifier, the same cationic starch derivative described therein. Withagitation, the emulsions of the mixed iso-alkenyl succinic acidanhydrides and the n-hexadecenyl succinic acid anhydride were added,respectively, at the hydropulper to bleached sulfate pulps having aconsistency of 1.5% and a freeness of 510. The emulsions of dodecenylsuccinic acid anhydride and dodecyl succinic acid anhydride were added,at the headbox, to a bleached sulfite pulp having a consistency of 0.5%and a freeness of 500. The resulting sheets, in each case, contained1.0% of the various sizing agents and 1.0% of the cationic starch asbased upon the dry weight of the pulp. Below is described thecomposition of the sheets prepared as well as the results obtained whenthe water resistance of these sheets was tested by means of the uraninedye test. A comparison of bleached sulfate sheets which had been sizedwith fortified rosin and alum is also offered.

Percent, Uranine Sheet No. Additives by wt., dye test 01' dry (time pulpin sec.)

Mixture of iso-alkenyl succinic acid 1. 1 anhydrides. f 120 Cationiccorn starch 1. 0 N-hexadecenyl succinic acid an- 1. 0 2 hydride. 118Cationic corn starch 1. 0 3 {Dodecenyl succinic acid anhvdride 1.0 no

Cationic corn Starch. 1. 0 4 {Dodeeyl succinic acid anhydrid 1. 0 105catioinig corn starch... 0 For i re rosin .0 5 {Alum 2.0 98

Example XII This example illustrates the use of our sizing agents incombination with a variety of cationic agents. It also demonstratestheir use in the treatment of paper pulp under a broad range of pHconditions.

An aqueous emulsion of IODSA was prepared by means of the proceduredescribed in Example I using, as the emulsifier, the corn starch acidester of octenyl succinic acid prepared by means of the proceduredescribed in Example II of U.S. Patent 2,661,349. With agitation,portions of this emulsion along with a quantity of one or more cationicagents were added to separate bleached sulfate stocks each having afreeness of 510 and a consistency of 0.5% but which were, however, at avariety of pH conditions. The resulting sheets, in each case, contained1.0% of IODSA and 1.0%, respectively, of the corn starch acid esteremulsifier and had a basis weight of 55 lbs/ream. The water resistanceof these sheets was then evaluated by means of the uranine dye test, asdescribed in Example I. The results of these tests as well as the natureof the cationic agents utilized and the pH of each pulp are presented inthe following table.

Percent, Uraninc Sheet Additives by wt., pH of dye test N o. of dry pulp(time in pulp see.)

Corn starch acid ester 1. 0 1 IODSA 1.0 5.0 101 Alum 2.0 Corn starchacid cstcr 1. 0 2 {IODSA 1. 0 5.0 101 Polyacrylamidc 0. 1 Corn starchacid ester 1. 0 3 {IODSA 1, 0 8. 0 55 Sodium aluminate 4 SA 5.0 96

In 2.0 1. 0 5 ODSA 1.0 6.0 82

1. 0 1. 0 6 ODSA 1.0 4.8 105 2. 0 1. 0 7 ODSA 1.0 7.0 102 A long chainamine 1. 0

Example XIII This example illustrates the improved strength which isobtained with the use of our sizing agents as compared with the strengthof unsized sheets as well as with sheets sized with mixtures offortified rosin and alum.

An aqueous emulsion of IODSA was prepared by means of the proceduredescribed in Example I wherein the same teritiary amine cationic starchdescribed therein was again used as the emulsifier. With agitation, thisemulsion was added, at the headbox, to an unbleached sulfate pulp havinga freeness of 550 and a consistency of 0.5%. The resulting sheetscontained 1.0% of both IODSA and the cationic starch as based upon thedry weight of the pulp and had a basis weight of 57 lbs/ream (24" x 36"--500 sheets). The water resistance of these sheets was then evaluatedby means of the uranine dye test.

The strength of these sheets was also determined using the Mullentester. In this apparatus a sheet of the paper is clamped between tworing shaped platens, thus leaving an exposed circular surface of paperunder which there is an inflatable rubber diaphragm. As air is pumpedinto this diaphragm it expands and comes into contact with the exposedsurface of the paper. Note is made of the pressure, in p.s.i., at whichthe diaphragm caused the paper to burst. The Mullen factor is thencalculated by dividing the latter figure by the basis weight of thepaper, a higher Mullen factor thus indicating a stronger paper.

Using the same paper making procedure as described above, comparablesheets were prepared which in this case were, however, sized with amixture of fortified rosin and aluim. Still other sheets were preparedwhich did not contain any sizing agents. These sheets served as a blank.The Mullen factor as well as the water resistance of these sheets wasalso determined and the following table presents the results of thesetests.

Percent, Uraninc Sheet Additives by wt., Mullen dve test No. of dryfactor (time in pulp sec.)

{Catronre corn starch L 36 200 1. 27 0 1. 23

The above data not only shows the improved strength and water resistanceof the sheets treated with our sizing agents, but also indicates thatthe use of rosin al um lrnixtnres actually decreases the strength of thesheets which contain these materials.

13 Example XIV This example illustrates the excellent resistance toacidic and alkaline solutions which is displayed by the paper which hasbeen treated with our novel sizing agents atoms and is selected from theclass consisting ttrirnethylene radicals and wherein R is groupcontaining more than five carbon of alkyl,

methylene and a hydrophobic alkenyl, aralkyl, and aralkenyl groups.

as compared w th that displayed by sheets which have been 5 i i gf ofclaim 1 w Sizing agent is sized with mixtures of fortified rosin andalum. e 3.11 g i i Fm. i t 1 d An aqueous emulsion of IODSA was preparedby means Paper e y g z of the procedure desc 'bed in Example I whereinthe m t 8 Y o t i 3. a same tertiary amine cationic starch describedtherein T aglent c wmpnses 10 was again used as the emulsifier. Withagitation, this 10 gf a Winds corresponding t Summit emulsion was addedto a bleached sulfate stock having a freeness of 500 and a consistencyof 0.5% The resulting sheets contained 0.5 of both IODSA and thecationic O starch and had a basis weight of 55 lbs/ream. 1 ii,

In testing the water resistance of these sheets by means of the uraninerlye test, the procedure described in EX- ample I was modified so thatin one case the paper swatch f containing the dye on its upper surfiacewas set afloat 0 in a by wt, aqueous solution of lactic acid rather thanthe distilled water which is nonmally employed. In Sim moth?modification !of ms mmne "(1Y6 test Pmce' wherein R is selected from theclass consisting of didure, additional swatches of the above describedsheets mathylene and @Lmethymene Zradicals and wmeredn is wmlefiet f a10%, by aquaous Sodium a hydrophobic group containing more than fivecarbon dmx'lde sollmonh a {tests were also P atoms and is selected theclass consisting of alkyl, comparable sheets WhlCh, in this case, hadbeen sized with alkenyl, aralkyl and aralkenyl ,gmupg a mum? q fi Beloware hswd 4. A paper product having intimately dispersed within thecompositions of the vanous sheets which were prethe Wet pulp thereof,prior w its conversion into a dry pared as well as the results obtainedwhen the water Web, (a) a sizing agent which comprises a cyouc dywapreslstance mess h was j by the boxylic acid \anhydride corresponding tothe structural above described modifications of the uramne dye test.@Omwla 0 Uranine dye test H Percent, (time in sec. 0 Sheet Additives bywt., I No. of dry 0 R-R pulp Lactic Sodium acid hydroxide O 1{idiliiiffi fiifffjj 3i? 106 2 {Fortified rosin i12.0 80 25 Alum whereinR is selected from the class consisting of dimethylene and tnirnethyleneradicals and where R is a hydrophobic group containing more than fivecarbon It was noted at an earlier point n this disclosure that atoms andi selected class i m f agkyl, various surfactants may also be utilizedas emulsifiers for talkenyl, aramyl and altagkenyl groups and (b) atleast the g agents our mven'mml- Thus, among R 0.025%, based on the dryweight of the pulp, of a ferent examples of surfactants which may beut1l1z6d, cationic agent; y list Plolyoxyethylem Sombltm moleate, P 'YU' 5. The paper product of claim 4, in which said cationic ethylenesonbrtol hexaoleate, polyoxyethylene sorbitol agent is seleoted t thegroup consisting f alum, laurate, and polyoxyethylene sonbitololeate-laurate. ammjnm chloride, long m f fly amines, sodium 011T f l is566?! pllovlde {he aluminate, polyacrylamide, animal glue, polyamidepolyl W {low/1 812mg f which We Operable mess, primary amine starchderivatives, secondary amine undel a Wide w 0f cofldmons and capable 9starch derivatives, tertiary amine stanch derivatives and providingpaper products which are characterized by their quaternary amine stawhdemivativei exceptionally high degree of water resistance. VariationsThe method of sizing pamlwhich comprises 1 m y be made'lfl @mpomons, p Fsteps of initrnately dispensing within the wet pulp, prior W' P Pdeplmmg from "1115 f ofufllls mwmlon which to the ultimate conversion ofsaid pulp into a dry web, lmmedfinly (a) a sizing agent which comprisesa cyclic dicarboxylic We claim: acid anhydride corresponding to thestructural formula 1. The method of sizing paper which comprises thestep of intimately dispersing within the wet pulp, prior to the ultimateconversion of said pulp into a dry web, a O sizing agent which comp "sesa cyclic dicarboxylic acid H anhydride corresponding to the structuraldormula 5 0 0 H II 0 o R-R 1 wherein R is selectedfrom the classconsisting of di- 0 methylene and trinrethylene radicals and wherein Ris a hydrophobic group containing more than live carbon wherein R isselected from the class consisting of diatoms and is selected from theclass consisting of alkyl,

alkenyl, aralkyl and aral'kenyl groups, and (b) at least 0.025%, basedon the dry Weight of the pulp, of a cationic :agent.

7. The method of claim 6, in which said cationic agent is selected fromthe group consisting of alum, aluminum chloride, long chain fattyamines, sodium aluminate, polyacrylamide, animal glue, polya-midepolymers, primary amine starch derivatives, secondary amine starchderivatives, tertiary amine starch derivatives and quaternary aminestarch derivatives.

UNITED STATES PATENTS Nathansohn Apr. 2, 1935 Prichard June 8, 1954Pattilloch Jan. 2, 1962 Copenhaver Feb. 20, 1962 FOREIGN PATENTS GreatBnitain Nov. 19, 1958

1. THE METHOD OF SIZING PAPER WHICH COMPRISES THE STEP OF INTIMATELYDISPERSING WITHIN THE WET PULP, PRIOR TO THE ULTIMATE CONVERSION OF SAIDPULP INTO A DRY WEB, A SIZING AGENT WHICH COMPRISES A CYCLICDICARBOXYLIC ACID ANHYDRIDE CORRESPONDING TO THE STRUCTURAL FORMULA